Scroll fluid machine

ABSTRACT

An object is to ensure reliable engagement of a pin and an engagement hole (ring) serving as a rotation prevention mechanism in a scroll fluid machine in which a turn radius of an orbiting scroll is constant. A scroll-type compressor (10) according to the present invention is provided with: a fixed scroll (24); an orbiting scroll (22) that revolves with respect to the fixed scroll (24); a main shaft (14) that includes an input shaft (14a) to which a driving force is transmitted, and an eccentric shaft (14c) that is offset by a predetermined amount with respect to the input shaft (14a) and that transmits the driving force to the orbiting scroll (22); and a pin-and-ring mechanism (27) that is provided between the orbiting scroll (22) and a housing (11) and that prevents rotation of the orbiting scroll (22). When a turn radius of the eccentric shaft (14c) of the main shaft (14) is ρs and a turn radius of a pin (27a), which is determined by the pin (27a) and ring (27b), is ρpin, the pin-and-ring mechanism (27) satisfies ρs&lt;ρpin.

TECHNICAL FIELD

The present invention relates to a scroll fluid machine that includes a so-called pin-and-ring type rotation prevention mechanism and that is used as a compressor, an expander, a fluid pump, and the like.

BACKGROUND ART

A scroll fluid machine includes a fixed scroll and an orbiting scroll. The fixed scroll and the orbiting scroll are each a disc-shaped end plate including a spiral wrap on a first surface thereof. Such a fixed scroll and an orbiting scroll face each other in a state in which the wraps are engaged with each other, and the orbiting scroll is caused to revolve with respect to the fixed scroll. The revolving of the orbiting scroll causes the capacity of a compressed space defined between the fixed and orbiting scrolls to be reduced, thus compressing fluid inside the space.

A pin-and-ring type rotation prevention mechanism is known as one of mechanisms that prevent rotation of the orbiting scroll. The pin-and-ring type rotation prevention mechanism prevents the rotation of the orbiting scroll by causing a plurality of pins to engage with a plurality of corresponding rings. The rings can be substituted by ring holes that are cylindrical openings.

With respect to a scroll fluid machine including this pin-and-ring type rotation prevention mechanism, Patent Document 1 proposes that the inner diameter of the ring be set such that a turn radius ρs of the pin determined by the pin and the ring is larger than a theoretical turn radius ρth of the orbiting scroll determined by the engagement between a wrap surface of the fixed scroll and a wrap surface of the orbiting scroll, and that the rings or the pins be displaced in a direction that causes torsion of the orbiting scroll with respect to the fixed scroll to be reduced.

According to Patent Document 1, since the turn radius ρs is set to be larger than the theoretical turn radius ρth, it is possible to prevent the wrap surface of the fixed scroll and the wrap surface of the orbiting scroll from failing to engage with each other. Further, as the rings or the pins are displaced in the direction that causes torsion of the orbiting scroll with respect to the fixed scroll to be reduced, the torsion of the orbiting scroll can be minimized.

PRIOR ART DOCUMENTS Patent Documents

Patent Document 1: JP 4745882 B

Patent Document 2: JP 06-68276 B (FIG. 2)

Patent Document 3: JP 2000-230487 A (FIG. 4)

SUMMARY OF THE INVENTION Problem to be Solved by the Invention

The scroll fluid machine is known to have a configuration in which the turn radius of the orbiting scroll is changeable or a configuration in which the turn radius is constant. The scroll fluid machine in which the turn radius is changeable causes the wrap of the orbiting scroll to be pressed against the wrap of the fixed scroll by using centrifugal force, or a reaction force generated by compression of the fluid being compressed. Incidentally, the scroll fluid machine of Patent Document 1 has the configuration in which the turn radius is changeable.

When assembling the scroll fluid machine including the pin-and-ring type rotation prevention mechanism, the pins need to be inserted into the rings. For example, assuming that the pins are provided on the orbiting scroll and the rings are provided in a housing of the scroll fluid machine, when the turn radius is changeable, even in a case where there are positional deviations between the pins and the rings, the pins can be inserted into the rings by making adjustments through changing the position of the orbiting scroll in the radial direction. Meanwhile, when the turn radius is constant, no adjustment can be made by changing the position of the orbiting scroll.

In light of the foregoing, an object of the present invention is to ensure reliable engagement of a pin and an engagement hole (ring) serving as a rotation prevention mechanism in a scroll fluid machine in which a turn radius of an orbiting scroll is constant.

Means for Solving the Problem

A scroll fluid machine of the present invention includes: a housing; a fixed scroll; an orbiting scroll configured to revolve with respect to the fixed scroll and assembled to define a compression space that compresses fluid between the orbiting scroll and the fixed scroll; a main shaft including an input shaft to which a driving force is input and an eccentric shaft offset by a predetermined amount with respect to the input shaft and that transmits the driving force to the orbiting scroll; and a rotation prevention mechanism for the orbiting scroll provided between the orbiting scroll and the housing. The housing is configured to house the fixed scroll, the orbiting scroll, the main shaft, and the rotation prevention mechanism.

In the scroll fluid machine of the present invention, the rotation prevention mechanism is configured such that a plurality of pins engage with a plurality of engagement holes into which each of the plurality of pins is inserted.

Further, when a turn radius of the eccentric shaft of the main shaft is ρs and a turn radius of the pin determined by the pin and the engagement hole is ρpin, the scroll fluid machine of the present invention satisfies ρs<ρpin.

When the turn radius of the eccentric shaft of the main shaft is ρs and the turn radius of the pin determined by the pin and the engagement hole is ρpin, since the scroll fluid machine of the present invention satisfies ρs<ρpin, the pin can be reliably inserted into the engagement hole when the scroll fluid machine is assembled.

In the scroll fluid machine of the present invention, one of the pin and the engagement hole is preferably displaced in a direction that causes torsion of the orbiting scroll with respect to the fixed scroll to be reduced.

In the scroll fluid machine of the present invention, of a wrap surface on an outer side and a wrap surface on an inner side of at least one of the fixed scroll and the orbiting scroll, the wrap surface whose gap is widened with respect to a theoretical curve is preferably thickened such that the gap is narrowed, and the wrap surface whose gap is narrowed with respect to the theoretical curve is preferably thinned such that the gap is widened.

In the scroll fluid machine of the present invention, when a theoretical turn radius determined by an engagement between the wrap surface of the fixed scroll and the wrap surface of the orbiting scroll is ρth, ρs<ρpin and ρs<ρth are preferably satisfied.

In the scroll fluid machine of the present invention, when the theoretical turn radius determined by the engagement between the wrap surface of the fixed scroll and the wrap surface of the orbiting scroll is ρth, ρs<ρpin<ρth is preferably satisfied.

In the scroll fluid machine of the present invention, when the theoretical turn radius determined by the engagement between the wrap surface of the fixed scroll and the wrap surface of the orbiting scroll is ρth, ρs<ρth<ρpin is preferably satisfied.

When the theoretical turn radius ρth of the orbiting scroll is constant, the scroll fluid machine of the present invention exhibits a significant effect.

Effect of Invention

When a turn radius of an eccentric shaft of a main shaft is ρs and a turn radius of a pin determined by the pin and an engagement hole is ρpin, since a scroll fluid machine of the present invention satisfies ρs<ρpin, the pin that serves as a rotation prevention mechanism can be reliably inserted into the engagement hole when the scroll fluid machine is assembled.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical cross-sectional view illustrating a schematic configuration of a scroll fluid machine according to an embodiment of the present invention.

FIG. 2 is a diagram of FIG. 1 as seen from the left to the right, and illustrates positional relationships between rings provided in an inner end face of a front case and pins provided on an outer end face of an orbiting scroll.

FIG. 3A is a diagram illustrating how torsion occurs in the orbiting scroll, and FIG. 3B is a diagram illustrating how a position of the ring is shifted so as to prevent torsion from occurring.

FIG. 4 is a diagram describing thickening and thinning of a wrap surface of the orbiting scroll, which are preferably adopted in the scroll fluid machine of the present embodiment.

FIG. 5 is a diagram describing a method for preventing contact between the wrap surface of the orbiting scroll and a wrap surface of a fixed scroll, which is preferably adopted in the scroll fluid machine of the present embodiment.

FIG. 6 is a diagram describing a method for preventing contact between the wrap surface of the orbiting scroll and the wrap surface of the fixed scroll, which is more preferably adopted in the scroll fluid machine of the present embodiment.

FIG. 7 is a diagram describing another method for preventing contact between the wrap surface of the orbiting scroll and the wrap surface of the fixed scroll, which is more preferably adopted in the scroll fluid machine of the present embodiment.

FIG. 8 is a diagram describing a condition in which the pins cannot be inserted into the rings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A scroll-type compressor 10 will be described below as an example of a scroll fluid machine of the present invention with reference to the appended drawings.

As illustrated in FIG. 1, the scroll-type compressor 10 includes a front housing 11 and a rear housing 12, and is provided with a housing 13 formed of the front housing 11 and the rear housing 12 integrally fastened and fixed together using bolts (not illustrated). An orbiting scroll 22, a fixed scroll 24, and the like that configure a scroll compression mechanism are housed inside the housing 13.

Inside the front housing 11, a main shaft 14 is rotatably supported around a rotational axis L1 thereof via a main bearing 15 and a sub bearing 16. The main shaft 14 is configured by a so-called crank shaft, and a first end side (a left side in FIG. 1) thereof is an input shaft 14 a. The input shaft 14 a passes through the front housing 11 and protrudes to the first end side. An electromagnetic clutch EC is mounted on a periphery of the input shaft 14 a, and motive power is intermittently provided between the electromagnetic clutch EC and a pulley 18, which is rotatably provided on an outer circumferential surface of a small-diameter boss portion 11 a disposed on the first end side of the front housing 11 via a bearing 17. The motive power is transmitted to the pulley 18 from an external driving source (not illustrated), such as an engine, via a V-belt or the like. This driving force is input to the input shaft 14 a.

Note that a mechanical seal 19 is provided between the main bearing 15 and the sub bearing 16, and the mechanical seal 19 forms a hermetic seal between the interior of the housing 13 and the atmospheric air.

Meanwhile, a large-diameter shaft portion 14 b is provided on a second end side (a right side in FIG. 1) of the main shaft 14, and the large-diameter shaft portion 14 b is integrally provided with an eccentric shaft 14 c that is offset by a predetermined amount with respect to the rotational axis L1 of the main shaft 14. Further, the large-diameter shaft portion 14 b and the input shaft 14 a of the main shaft 14 are each rotatably supported by the front housing 11 via the main bearing 15 and the sub bearing 16.

Further, the orbiting scroll 22 is connected to the eccentric shaft 14 c via a balance bushing 20 and a drive bearing 21, and rotation of the main shaft 14 causes the orbiting scroll 22 to revolve.

An interval between a central axis L2 of the eccentric shaft 14 c and the rotational axis L1 of the main shaft 14 is a turn radius ρs of the eccentric shaft 14 c of the main shaft.

A balance weight 20 a is formed on a balance bushing 20 so as to eliminate an unbalanced load generated by the orbiting scroll 22 being driven to revolve, and the balance weight 20 a is caused to revolve as a result of the orbiting scroll 22 being driven to revolve.

A pair of the fixed scroll 24 and the orbiting scroll 22, which configure a scroll-type compression mechanism 23, are housed inside the housing 13.

The fixed scroll 24 is provided with a fixed end plate 24 a and a spiral-shaped fixed wrap 24 b erected from the fixed end plate 24 a. Meanwhile, the orbiting scroll 22 is provided with an orbiting end plate 22 a and a spiral-shaped orbiting wrap 22 b erected from the orbiting end plate 22 a.

The fixed scroll 24 and the orbiting scroll 22 are assembled together in a state in which the centers thereof are separated from each other by the turn radius, and the fixed wrap 24 b and the orbiting wrap 22 b engage with each other with a phase difference of 180 degrees between them. As a result, a pair of compression chambers C, which are partitioned by the fixed end plate 24 a, the orbiting end plate 22 a, the fixed wrap 24 b, and the orbiting wrap 22 b, are formed between the fixed scroll 24 and the orbiting scroll 22 so as to be symmetrical with respect to the scroll centers. In the compression chambers C, a refrigerant that serves as a fluid is compressed.

The fixed scroll 24 is fixed to the inner surface of the rear housing 12 via a bolt 25. The orbiting scroll 22 is connected to the main shaft 14 as a result of the eccentric shaft 14 c provided on the first end side of the main shaft 14 being fitted into a boss portion 26 provided in the rear surface of the orbiting end plate 22 a via the balance bushing 20 and the drive bearing 21.

Further, of the orbiting scroll 22, the rear surface of the orbiting end plate 22 a is supported by a thrust receiving surface 11 b that is formed on the front housing 11, and using a pin-and-ring mechanism 27 that serves as a rotation prevention mechanism interposed between the thrust receiving surface 11 b and the rear surface of the orbiting scroll 22, the orbiting scroll 22 is configured to revolve with respect to the fixed scroll 24 while being inhibited from rotating.

Note that, in the scroll-type compressor 10 in which the turn radius of the orbiting scroll 22 is constant, a minute gap is provided between the orbiting wrap 22 b and the fixed wrap 24 b in order to prevent the orbiting wrap 22 b and the fixed wrap 24 b from being damaged as a result of coming into contact with each other.

This pin-and-ring mechanism 27 is provided with pins 27 a and rings 27 b. Pin holes 11 c for erecting the pins 27 a are provided in the rear surface of the orbiting end plate 22 a of the orbiting scroll 22, and ring holes 27 c into which the rings 27 b are fitted are provided in the front housing 11.

An interval between a central axis L3 of the pin 27 a and a central axis L4 of the ring 27 b is a turn radius ρpin of the pin that is determined by the pin and an engagement hole, and the pin 27 a revolves at the turn radius ρpin as a result of the the orbiting scroll 22 revolving.

Note that the pin holes 11 c and ring holes 27 c are provided at a plurality of locations along the circumferential direction, which are four locations in the present embodiment, but they can be provided ranging from three to six locations.

Further, a discharge port 24 c, which discharges compressed refrigerant gas, is provided as an opening in a central portion of the fixed end plate 24 a of the fixed scroll 24, and a discharge lead valve (not illustrated) is provided in this discharge port 24 c, in the fixed end plate 24 a.

In addition, a seal member (not illustrated), such as an O-ring, is mounted on the rear surface of the fixed end plate 24 a of the fixed scroll 24 so as to be in close contact with the inner surface of the rear housing 12, and a discharge chamber 29 that is partitioned from an internal space (hermetically sealed space) of the housing 13 is formed between the seal member and the rear housing 12. As a result, a configuration is obtained in which the internal space of the housing 13 apart from the discharge chamber 29 functions as an intake chamber 30.

The refrigerant gas that returns from a refrigeration cycle via an intake port (not illustrated) provided in the front housing 11 is taken into the intake chamber 30, and is taken into the compression chambers C formed between the fixed scroll 24 and the orbiting scroll 22 through this intake chamber 30.

Note that a seal member, such as an O-ring, is provided on a joining surface between the front housing 11 and the rear housing 12, and the seal member hermetically seals the intake chamber 30 inside the housing 13 from the atmospheric air.

The electromagnetic clutch EC sucks an armature (not illustrated), which is formed of a magnetic material, against a contact surface of a rotor 43 using the magnetic force of an electromagnetic coil 41, and integrally connects the armature and the rotor 43, thereby transmitting the motive power.

In the electromagnetic clutch EC, electricity supplied to the electromagnetic coil 41 is turned on and off on the basis of instructions from an external controller. For example, when an air-conditioning device is switched from an off-state to an on-state, the electricity supplied to the electromagnetic coil 41 is turned on the basis of the instruction from the external controller. As a result, the armature 42 and the rotor 43 are integrally connected to each other by the magnetic force of the electromagnetic coil 41, and a rotational driving force transmitted from the external driving source is transmitted to the main shaft 14.

The scroll-type compressor 10 that is configured as described above operates in the following manner.

The rotational driving force transmitted from the external driving source to the pulley 18 is input to the input shaft 14 a of the main shaft 14 via the electromagnetic clutch EC, and causes the main shaft 14 to rotate. Then, the orbiting scroll 22, which is connected to the eccentric shaft 14 c of the main shaft 14 via the balance bushing 20, a drive bushing 14 d, and the drive bearing 21, is caused to revolve with respect to the fixed scroll 24 while being inhibited from rotating by the pin-and-ring mechanism 27. Note that this driving mechanism of the main shaft 14 is only an example, and a mechanism may be adopted, for example, in which an electric motor that includes a rotor and a stator is provided inside the housing 13 as a driving source, and the main shaft 14 is directly rotated by this rotor.

Then, as a result of the revolving of the orbiting scroll 22, the refrigerant gas inside the intake chamber 30 is taken into the compression chambers C that are formed at the outermost circumference in the radial direction. After the intake of the refrigerant gas is terminated at a predetermined turn angle position, the compression chambers C are moved toward the center side while the capacity thereof is gradually reduced in the circumferential direction and in the wrap height direction. During this period, the refrigerant gas is compressed, and when the compression chamber C reaches a position communicating with the discharge port 24 c, the discharge lead valve is pressed open and the compressed gas is discharged into the discharge chamber 29. This compressed refrigerant gas is discharged to the outside of the compressor through a discharge port (not illustrated) provided in the rear housing 12.

With the scroll-type compressor 10 of the present embodiment, at the time of the assembly thereof, in order to ensure that the pins 27 a of the pin-and-ring mechanism 27 are reliably inserted into the engagement holes inside the rings 27 b, the turn radius ρs of the eccentric shaft 14 c of the main shaft 14 and the turn radius ρpin of the pin 27 a determined by the pin 27 a and the engagement hole of the ring 27 b, satisfy Relationship (1).

ρs<ρpin   Relationship (1)

This relationship will be described below with reference to FIG. 2 and FIG. 8. Note that FIG. 8 illustrates an example in which the turn radius ρs and the turn radius ρpin satisfy Relationship (2) that expresses an opposite relationship to that of the present embodiment.

ρs>ρpin   Relationship (2)

First, FIG. 2 will be described.

As described above, the pins 27 a of the pin-and-ring mechanism 27 are fixed to the orbiting end plate 22 a of the orbiting scroll 22, and the orbiting scroll 22 revolves in accordance with the revolving of the eccentric shaft 14 c of the main shaft 14. Thus, the pins 27 a also revolve as a result of the revolving of the eccentric shaft 14 c, and at this time, the turn radius of the pin 27 a is ρs. When this is applied upon assembling the scroll-type compressor 10, the pins 27 a can move on the circumference of the turn radius ρs in accordance with the position of the orbiting scroll 22.

Meanwhile, although the pins 27 a configure the pin-and-ring mechanism 27 as a result of being inserted into the rings 27 b, namely, into the interior of the engagement holes, since the turn radius of the pins 27 a of the pin-and-ring mechanism 27 is ρpin, the pins 27 a need to be positioned within a range of the turn radius ρpin at the time the scroll-type compressor 10 is assembled. Since the pins 27 a can move on the circumference of the turn radius ρs, in order to insert the pins 27 a into the engagement holes of the rings 27 b, Relationship (1) expressing that the turn radius ρpin is larger than the turn radius ρs needs to be satisfied.

In FIG. 2, it is assumed that the orbiting scroll 22 is present on the right side of the drawing, as illustrated by a dashed line arrow. In the following description, in the same manner as described above, the dashed line arrow indicates the position at which the orbiting scroll 22 is present.

Contrary to Relationship (1), when Relationship (2) is satisfied, namely, when the turn radius ρpin is smaller than the turn radius ρs, as illustrated in FIG. 8, the pins 27 a cannot be inserted into the rings 27 b.

Note that in a case where each member, including the pin 27 a and the ring 27 b, can be manufactured without any deviation, even when the turn radius ρs is equal to the turn radius ρpin, as illustrated in Relationship (3), the pins 27 a can be inserted into the rings 27 b. However, since it is difficult to manufacture each of the members accurately without any deviation in reality, the present embodiment makes it a condition that the turn radius ρpin is larger than the turn radius ρs. ρs=ρpin . . . Relationship (3)

As described above, according to the present embodiment, by setting the turn radius ρpin to be larger than the turn radius ρs, the pins 27 a are reliably inserted into the rings 27 b (engagement holes), thus facilitating the assembly of the scroll-type compressor 10.

Note that, although to what degree the turn radius ρpin is supposed to be larger than the turn radius ρs is not determined by dimensions of the scroll-type compressor 10 or the like, the degree is determined on the basis of a range within which the pins 27 a and the rings 27 b can fulfill the function of preventing the rotation of the orbiting scroll 22.

Specifically, the turn radius ρpin and the turn radius ρs can be set so as to satisfy Relationship (A) below.

ρpin−ρs<δm×Rpin/b   Relationship (A)

ρpin: Turn radius of the pin 27 a

ρs: Turn radius of the eccentric shaft 14 c

δm: Initial gap between the wrap surfaces of the orbiting scroll 22 and the fixed scroll 24

b: Base radius of involute curve

α: Helix angle between the orbiting scroll 22 and the fixed scroll 24

Rpin: Distance from the center of the eccentric shaft 14 c to the center of the pin 27 a or the center of the ring 27 b

The above-described Relationship (A) will be described below.

The initial gap between the wrap surfaces of the fixed scroll 24 and the orbiting scroll 22 is referred to as δm.

For example, provided that the wrap surfaces of the fixed scroll 24 and the orbiting scroll 22 are formed by involute curves, when the base radius thereof is b and a torsion amount of the fixed/orbiting scrolls is α (rad), the gap between the fixed scroll and the orbiting scroll is reduced on one side (an inner side of the fixed scroll) by an amount equivalent to b×α and widened on the other side (an outer side of the fixed scroll) by an amount equivalent to b×α.

Thus, the maximum tolerance value of torsion of the scrolls needs to satisfy Relationship (B) below.

δm>b×α  Relationship (B)

Further, torsion α of the scrolls is determined by a set value A (A=ρpin−ρs) of the initial ρpin and ρs and an installation position radius Rpin of the pins and rings, and the relationship thereof is expressed by Relationship (C).

α=Δ/Rpin   Relationship (C)

Thus, the above-described Relationship (A) is defined by Relationships (B) and (C), and when Relationship (A) is satisfied, the wrap surfaces of the scrolls do not come into contact with each other theoretically.

Note that, although the pins 27 a are provided on the orbiting scroll 22 and the rings 27 b are provided in the front housing 11 in the scroll-type compressor 10, even when the rings 27 b are provided in the orbiting scroll 22 and the pins 27 a are provided on the front housing 11 in an opposite manner to the above, the relationship expressed by Relationship (1) still applies in the same manner. Further, the ring holes can be formed instead of using the rings 27 b.

Besides the above-described embodiment, as long as there is no departure from the spirit and scope of the present invention, configurations explained in the above-described embodiment can be selected as desired, or can be changed to other configurations as necessary. Some of preferable configurations that can be applied to the present invention will be described below.

In the scroll-type compressor 10, as a result of the orbiting scroll 22 revolving, a torsional moment in the rotational direction acts on the orbiting scroll 22. For example, as illustrated in FIG. 3A, when the orbiting scroll 22 undergoes a right-handed rotation R (clockwise rotation), a right-handed rotation moment acts on the orbiting scroll 22. Since the pin 27 a satisfies Relationship (1), a gap corresponding to ρpin−ρs is provided between the pin 27 a and the inner wall of the ring 27 b. Thus, the orbiting scroll 22 rotates with respect to the fixed scroll 24 by an amount equivalent to the gap, and as a result, torsion α is generated.

As a result of a gap of the wrap surface on the outer side of the fixed scroll 24 and a gap of the wrap surface on the inner side of the fixed scroll 24, which seals the compression chambers C, changing, there is a possibility of a deterioration in the compression performance of the scroll-type compressor 10. Incidentally, as illustrated in FIG. 3A, when there is torsion of the orbiting scroll 22 in the right-handed rotation direction, the gap of the wrap surface on the outer side of the fixed scroll 24 becomes larger than the gap of the wrap surface on the inner side thereof, and when there is torsion of the orbiting scroll 22 in the left-handed rotation direction, the gap of the wrap surface on the inner side of the fixed scroll 24 becomes larger than the gap of the wrap surface on the outer side thereof.

Here, the gap of the wrap surface on the outer side of the fixed scroll 24 means a gap with the wrap surface on the inner side of the orbiting scroll 22 (illustrated by (3) and (4) in FIG. 4), and the gap of the wrap surface on the inner side of the fixed scroll 24 means a gap with the wrap surface on the outer side of the orbiting scroll 22 (illustrated by (1) and (2) in FIG. 4).

Thus, in the present invention, as illustrated in FIG. 3B, the pin 27 a (or the ring 27 b) is preferably displaced by an amount equivalent to Δ in a direction that causes torsion α to be reduced. In this way, by twisting back the torsion of the right-handed rotation direction toward the left-handed rotation direction by the amount equivalent to the change Δ, torsion α is reduced, and the gaps of the wrap surfaces on the outer and inner sides of the fixed scroll 24 can be balanced. As a result, the deterioration in the compression performance of the scroll-type compressor 10 is inhibited, and at the same time, a pressure balance between the outer side and the inner side is improved.

The next configuration described below is also related to torsion, and the configuration is a countermeasure when assuming that the occurrence of the torsion is allowed.

As described above, when torsion of the orbiting scroll 22 occurs, the gaps on the inner and outer sides of the fixed scroll 24 become uneven.

For example, as illustrated in FIG. 4, when torsion of the orbiting scroll 22 occurs in the left-handed direction, the gap on the inner side (the side illustrated by arrows (1) and (2)) of the fixed scroll 24 becomes wider, and the gap on the outer side (the side illustrated by arrows (3) and (4)) thereof becomes narrower. Normally, the inner sides and the outer sides of the orbiting scroll 22 and the fixed scroll 24 are formed to follow theoretical curves (solid lines in FIG. 4) that correspond to the involute curves. However, the present embodiment proposes that the shapes of the outer sides and the inner sides be formed into shapes corresponding to torsion, instead of being formed to follow the theoretical curves. In other words, as illustrated by a long dashed double-short dashed line in FIG. 4, the inner side of the fixed scroll 24, where the gap is widened due to torsion, is made to be thicker (24 d) than the theoretical curve so as to narrow the gap, and on the contrary, the outer side of the fixed scroll 24, where the gap is narrowed due to torsion, is made to be thinner (24 e) than the theoretical curve so as to widen the gap. Note that FIG. 4 mainly intends to illustrate the thickening (24 d) and the thinning (24 e), and although the wrap surfaces are in contact with each other due to the thickening (24 d) and the thinning (24 e), this only illustrates an example and is not a factor that limits the present invention.

As described above, the gaps of the outer side and the inner side of the fixed scroll 24 can be balanced, and as a result, the deterioration in the compression performance of the scroll-type compressor 10 is inhibited, and at the same time, the pressure balance between the outer side and the inner side is improved.

Note that degrees of the thickening and the thinning may be determined in accordance with a specification of the scroll-type compressor 10.

Next, as described above, in the scroll-type compressor 10 in which the turn radius of the orbiting scroll 22 is constant, the orbiting wrap 22 b of the orbiting scroll 22 and the fixed wrap 24 b of the fixed scroll 24 are required not to come into contact with each other and to have a minute gap therebetween.

Thus, as illustrated in FIG. 5, the present embodiment preferably satisfies both ρs<ρpin . . . Relationship (1) and ρs<ρth . . . Relationship (4). Note that ρth is a theoretical turn radius of the orbiting scroll 22 that is determined by the engagement between the orbiting scroll 22 and the fixed scroll 24.

By satisfying Relationship (4), the contact between the orbiting scroll 22 and the fixed scroll 24 can be reliably avoided.

When ρs<ρpin . . . Relationship (1) and ρs<ρth . . . Relationship (4) are satisfied, the relationship between ρpin and ρth can be selected from one of Relationship (5) and Relationship (6) below.

ρpin≤ρth   Relationship (5)

ρpin>ρth   Relationship (6)

Note that when Relationship (5) is applied to Relationship (1), it can be expressed as ρs<ρpin<ρth . . . Relationship (7), and when Relationship (6) is applied to Relationship (1), it can be expressed as ρs<ρth<ρpin . . . Relationship (8).

A case in which Relationship (5) is selected is illustrated in FIG. 6. In this case, since torsion of the orbiting scroll 22 can be made smaller, the gaps of the outer side and the inner side of the fixed scroll 24 can be balanced, and a stable operation of the scroll-type compressor 10 can be achieved.

Further, a case in which Relationship (6) is selected is illustrated in FIG. 7. In this case, the initial gap δm of the orbiting scroll 22 and the fixed scroll 24 can be made smaller, the deterioration in the performance of the scroll-type compressor can be inhibited.

Further, specific configurations of the scroll-type compressor 10 are only examples of the present invention, and shapes, dimensions and the like of each of the components that configure the scroll-type compressor may be decided as desired.

For example, in the scroll-type compressor 10, although the pins 27 a are provided on the orbiting scroll 22 and the engagement holes are provided having the rings 27 b in the fixed scroll 24, the pins 27 a can be provided on the fixed scroll 24 side, and the engagement holes can be provided on the orbiting scroll 22 side. In this case, the engagement holes can also be directly provided in the orbiting end plate 22 a of the orbiting scroll 22 without providing the rings 27 b.

Further, although the present embodiment illustrates the mechanism in which one pin engages with one ring (engagement hole), among the pin-and-ring type rotation prevention mechanisms, the present invention is not limited to this example, and for example, can be applied to a rotation prevention mechanism in which a plurality of pins (two pins, for example) engage with one ring, as described in Patent Document 2.

Further, although the present embodiment illustrates the mechanism in which positions of the pins are fixed, among the pin-and-ring type rotation prevention mechanisms, the present invention is not limited to this example, and for example can be applied to a rotation prevention mechanism that regulates a maximum displacement of the pins while allowing displacement of the pins in the radial direction, as illustrated in Patent Document 3.

REFERENCE SIGNS

-   10 Scroll-type compressor -   11 Front housing -   11 a Small-diameter boss portion -   11 b Thrust receiving surface -   11 c Pin hole -   12 Rear housing -   13 Housing -   14 Main shaft -   14 a Input shaft -   14 b Large-diameter shaft portion -   14 c Eccentric shaft -   14 d Drive bushing -   15 Main bearing -   16 Sub bearing -   17 Bearing -   18 Pulley -   19 Mechanical seal -   20 Balance bushing -   20 a Balance weight -   21 Drive bearing -   22 Orbiting scroll -   22 a Orbiting end plate -   22 b Orbiting wrap -   23 Scroll-type compression mechanism -   24 Fixed scroll -   24 a Fixed end plate -   24 b Fixed wrap -   24 c Discharge port -   25 Bolt -   26 Boss portion -   27 Pin-and-ring mechanism -   27 a Pin -   27 b Ring -   27 c Ring hole -   28 Retainer -   29 Discharge chamber -   30 Intake chamber -   41 Electromagnetic coil -   43 Rotor -   C Compression chamber -   L1 Rotational axis -   L2 Central axis -   L3 Central axis -   L4 Central axis -   EC Electromagnetic clutch -   ρpin Turn radius -   ρs Turn radius 

1. A scroll fluid machine comprising: a housing; a fixed scroll; an orbiting scroll configured to revolve with respect to the fixed scroll and assembled to define a compression space that compresses fluid between the orbiting scroll and the fixed scroll; a main shaft including an input shaft to which a driving force is input, and an eccentric shaft offset by a predetermined amount with respect to the input shaft and that transmits the driving force to the orbiting scroll; and a rotation prevention mechanism for the orbiting scroll provided between the orbiting scroll and the housing, wherein the housing is configured to house the fixed scroll, the orbiting scroll, the main shaft, and the rotation prevention mechanism, the rotation prevention mechanism is configured such that a plurality of pins engage with a plurality of engagement holes into which each of the plurality of pins is inserted, and when a turn radius of the eccentric shaft of the main shaft is ρs and a turn radius of the pin determined by the pin and the engagement hole, is ρpin, ρs<ρpin is satisfied.
 2. The scroll fluid machine according to claim 1, wherein one of the pin and the engagement hole is displaced in a direction that causes torsion of the orbiting scroll with respect to the fixed scroll to be reduced.
 3. The scroll fluid machine according to claim 1, wherein of a wrap surface on an outer side and a wrap surface on an inner side of at least one of the fixed scroll and the orbiting scroll, the wrap surface whose gap is widened with respect to a theoretical curve is thickened such that the gap is narrowed, and the wrap surface whose gap is narrowed with respect to the theoretical curve is thinned such that the gap is widened.
 4. The scroll fluid machine according to claim 1, wherein when a theoretical turn radius determined by an engagement between the wrap surface of the fixed scroll and the wrap surface of the orbiting scroll is ρth, ρs<ρpin and ρs<ρth are satisfied.
 5. The scroll fluid machine according to claim 1, wherein when a theoretical turn radius determined by an engagement between the wrap surface of the fixed scroll and the wrap surface of the orbiting scroll is ρth, ρs<ρpin≤ρth is satisfied.
 6. The scroll fluid machine according to claim 1, wherein when a theoretical turn radius determined by an engagement between the wrap surface of the fixed scroll and the wrap surface of the orbiting scroll is ρth, ρs<ρth<ρpin is satisfied.
 7. The scroll fluid machine according to claim 1, wherein the theoretical turn radius ρth of the orbiting scroll is constant.
 8. The scroll fluid machine according to claim 1, wherein of a wrap surface on an outer side and a wrap surface on an inner side of the fixed scroll, the wrap surface whose gap is widened with respect to a theoretical curve is thickened such that the gap is narrowed, and the wrap surface whose gap is narrowed with respect to the theoretical curve is thinned such that the gap is widened.
 9. The scroll fluid machine according to claim 1, wherein of a wrap surface on an outer side and a wrap surface on an inner side of the orbiting scroll, the wrap surface whose gap is widened with respect to a theoretical curve is thickened such that the gap is narrowed, and the wrap surface whose gap is narrowed with respect to the theoretical curve is thinned such that the gap is widened.
 10. The scroll fluid machine according to claim 7, wherein of a wrap surface on an outer side and a wrap surface on an inner side of the fixed scroll, the wrap surface whose gap is widened with respect to a theoretical curve is thickened such that the gap is narrowed, and the wrap surface whose gap is narrowed with respect to the theoretical curve is thinned such that the gap is widened.
 11. The scroll fluid machine according to claim 7, wherein of a wrap surface on an outer side and a wrap surface on an inner side of the orbiting scroll, the wrap surface whose gap is widened with respect to a theoretical curve is thickened such that the gap is narrowed, and the wrap surface whose gap is narrowed with respect to the theoretical curve is thinned such that the gap is widened. 